In business activities, the use of business data generated in a large amount becomes essential. Therefore, a system which performs an analysis process on a database (hereinafter, referred to as a “DB”) where a large amount of the business data is stored has been already contrived.
In the analysis process, a database management system (hereinafter, referred to as a “DBMS”) receives a query and issues a data read request to a storage device storing the DB.
As a technique for of reducing latency for data read in an execution of one query, a technique disclosed in PTL 1 is known. According to PTL 1, a DBMS generates a plan (hereinafter, referred to as a “query execution plan”) which is a combination of a plurality of database operations (hereinafter, referred to as “DB operations”) necessary for executing a query, dynamically generates tasks of executing the DB operations every time of reading data necessary for the query execution, and multiplexes data read requests by executing the tasks in parallel.